fixed speech to text and true/false check for Chrome

Chrome's x-webkit-speech was deprecated, replaced it with javascript API
added functionality:
now actively tracks interim results and displays them to the user
added variety of error messages and prompts

fixes CNVS-13432

test plan:
- use Chrome (Version 35 or 36)
- navigate to an assignment, then to speedgrader
- click the microphone/pencil icon under the comment box
- dialog should pop up. Click record (then 'allow' if prompted)
- begin speaking
- interim results should appear in blue while talking
- final results should turn black
- when you hit stop, spoken text should appear in comment box
- should generate error for mic not allowed or no text spoken
- should bring up error if recording times out after long silence
- cancel button should discard spoken text w/out adding comment
- ensure mic does not appear in FF, Safari, or IE

Change-Id: I46eae92892dd37e0a3906023150653aaaf2e2ece
Reviewed-on: https://gerrit.instructure.com/38833
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Mike Nomitch <mnomitch@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: Sean Lewis <slewis@instructure.com>
Product-Review: Hilary Scharton <hilary@instructure.com>